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Case Study
Gwynt y Môr OWF (2014) - 37 cables / 41,700 m (ICC)
Towards the end of 2013 CT Offshore was contracted by RWE Npower Renewable to carry out free-
laying, installation and burial of 63 cables of the total 161 inter-array cables at one of Europe’s largest
offshore wind farms, Gwynt y Môr OWF (GyM).
Many challenges were met especially with the demanding soil conditions on the GyM project.
With Fugro as trenching partner, CT Offshore was able to overcome these challenges and accomplished
the installation and burial of the inter-array cables in the safest and most efficient way.
CT Offshore where also brought into the project when most of the towers were in position. This also
presented another challenge. Due to the limited headroom within the tower hang off area and the cable
type not being flexible, up to 9 hours of stripping back the cable to allow safe connection resulted.
1. Scope of Work
Free-laying, installation and burial of 63 inter-array cables, using the CPS system ‘Teklink’ from Tekmar.
Cable load-out
Pre-lay Multibeam survey (MBES)
Rigging of towers and messenger wire work
Array cable installation
Post-lay inspection (PLI)
Optical time delay reflection (OTDR) test
Post-lay burial (PLB)
ROV post-burial survey
Activation of Tekmar seals by use of divers
Vessels and equipment utilized
Cable Installation: CLV SIA
Survey, Trenching: MV FUGRO SALTIRE
Execution period, surface laid cables
Start-up Dec. 2013 (initial delay due to 3 UXOs in park)
Completed 5 June 2014
Due to another contracted assignment to BKR1, CLV SIA had a cut-off date 5 June to meet.
In the time available she and the crew managed to install 37 cables out of the 63 contracted.
Team work with Fugro
To carry out the post lay burial of the cables in
scope, CT Offshore entered into a framework
agreement with Fugro Subsea Services Limited, as
principle subcontractor.
They brought in the vessel MV SALTIRE to bury the
cables subsequently using their Q1400 trencher.
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2. Raw Installation Time – 37 ICC Cables (Gwynt y Môr)
2.1 Improving learning curve
2.2. Min. / Average installation time (hrs.) of 37 cables.
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2.3. Assigned in Project – Overall time consumption (according to DPR report structure)
2.4. Assigned in Project – Overall time consumption, in further details (according to DPR report structure)
Challenges, UXOs
Due to three UXOs in the offshore wind park the work was delayed until safely cleared. Then the first
cable was laid 12 March 2014 and 37 cables were completed by 5 June 2014, when CLV SIA had to leave
site for another contracted assignment. Fugro Saltire completed the burial of the 37 cables by 1 July
2014.
